Telephone-exchange system.



L. H. JOHNSON TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 26. 1916.

Patented Jan. 16, 1917.

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ENTTED ETATEB; PATENT @EETQE.

LEWIS H. JOHNSON, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR TO WESTERNELECTRIC COMPANY, INCORPORATED, OF NEVV' YORK, N. Y., A CORPORATION OFNEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented an. is, 1.917.

Application filed May 26, 1916. Serial No. 99,978.

To all whom it may concern:

Be it known that I, LEWIs H. JOHNSON, a citizen of the United States,residing at Bloomfield, in the county of Essex and State of New Jersey,have invented certain new and useful Improvements in Telephone-Ex changeSystems, of which the following is a full, clear, concise, and exactdescription.

This invention relates to telephone exchange systems and moreparticularly to such systems of the centralenergy type in which anoperators telephone set is automatically connected to and disconnectedfrom a calling telephone line.

The object of this invention is the provision of means for increasingthe eficiency of the operators of a telephone exchange and forfacilitating the completing of connections between subscribers.

In accordance with this invention, a telephone exchange system, in whichthe operators telephone set is automatically connected to a callingtelephone line upon the connection of a link circuit therewith, isprovided with circuits and apparatus, so organized that, while theoperators telephone set is connected to one calling telephone line, itcan not be connected to any other calling line, but a second connectionmay be.pre pared during the existence of the first so that upon thedisconnection of the operators telephone set from the first callingline, it will be immediately connected to the calling line forming apart of the prepared connection.

This invention is an improvement on that disclosed in the application ofHenry P. Clausen, Ser. No. 59,972, filed November 6, 1915, in that lessapparatus is required for accomplishing the desired result.

More specifically, this invention contemplates a telephone exchangesystem in which there are link circuits for interconnecting the linesand a relay associated with each link circuit for automaticallyconnecting the operators telephone set with the talking strands thereofwhen connected with a call ing telephone line. Each link circuit is alsoprovided with a second relay, the opera tion of any one of the listeningrelays conditioning the'second relay of all other link circuits foroperation, the second relay of any of the other cord circuits being thenoperated upon the connection of its associated link circuit with,annther calling. line- The operation of this secondrelay. of anotherlink circuit prevents the operation of the listening relay thereof,thereby preventrupter mechanism in circuit with the signaling device tofurnish a signal to the operator.

This invention is illustrated in the accompanying drawing in which thereare shown ordinary subscribers lines A, B, C and D (subscribers lines B,C, and D being indicated merely by the answering jacks thereof), and twocord circuits E and F for interconnecting the subscribers lines. Theappartus of each cord circuit is exactly alike, and the same referencecharacters will be used in each to indicate the same apparatus.

Assuming that subscriber A wishes to converse with subscriber B, A willsignal the central office in the usual manner, whereupon the operatorwillinsert the answering plug of the cord circuit E into the jackassociated with As line, causing the operation of sleeve relay 5 andsupervisory relay 6. The operation of supervisory relay 6 causes theoperation of listening relay 7 over a circuit from battery throughcontact 8 of relay 9, lower winding of relay 7, left-hand normal contactof relay 10, alternate contact of supervisory relay 6 and supervisorylamp 11 to ground. The operation of the listening relay 7 connects anoperators telephone set 12 t0 the talking strands of cord circuit E,

- and by the engagement of its lower armature with contact 13, connectsbattery to one terminal of the right-hand winding of relay 10 of thecord circuit F by way of contact 13 of relay 7 (cord circuit E), commonconductor 14, contact 15 of relay 7 (cord circuit F), right-hand normalcontact of relay 9 to one terminal of the-right-hand winding of relay 10of cord circuit F, thereby conditioning this relay for operation. Itwill be, understood that the relay 10 in each of the cord circuits ofthis position other than the cord circuit E, will be conditioned foroperation by the operation of the listening relay 7 of the cord circuitE. After ascertaining that subscriber A wishesto be connected to the 1sf. ubscriber. Ba hefire atar nser s ha calling plug into the jack of Bsline, causing the operation of relay 9, which opens the normal contactsthereof and closes the lefthand alternate contact. The opening ofcontact 8 of relay 9 removes the short circuit from the middle windingof relay 7, whereupon this relay receives current from battery throughthe middle and lower windings, normal left-hand contact of relay 10,alternate contact of supervisory relay 6 and supervisory lamp 11. Themiddle and lower windings of listening relay 7 are connected in seriesopposing, so that when the circuitis completed through both of thesewindings, the magnetizing eflect produced by one is neutralized by thatof the other, so that the relay releases. Upon the release thereof,battery is removed from the common conductor 14. The closure of theleft-hand alternate contact of relay 9 causes supervisory lamp 21 tolight. The operator may now actuate ringing key 22 to send ringingcurrent out over Bs line to operate the call bell thereat. Subscriber B,in responding, removes the receiver from the switch hook, causing theoperation of supervisory relay 23 to elface supervisory lamp 21. Uponthe completion of the conversation, subscribers A and B restore thereceivers to the switch hooks, causing the supervisory lamps 11 and 21to light to furnish disconnect signals. The operator then withdraws theplugs from the jacks, whereupon all apparatus returns to normal.

Suppose that while the operator was busy completing connections betweensubscribers A and B, but before the calling plug of cord circuit E wasinserted into the jack of Bs line, subscriber C had initiated a call.The operator could take up this call by inserting the answering plug ofcord circuit F into the jack of Us line, thereby causing the operationof sleeve relay 5. The operation of this relay causes the operation ofrelay 10 over a circuit from battery, through contact 13 of relay 7 (incord circuit E), common conductor 14-, contact 15 of relay 7 (in cordcircuit 1*), right-hand normal contact of re lay 9, right-hand windingof relay 10 and contact of relay 5 to ground. Supervisory relay 6 ofcord circuit F will also have operated upon the insertion of the callingplug into the jack of Us line, so that with relays 6 and 10 operated,supervisory lamp 11 is caused to flash intermittently, due to interrupter 25 being in circuit with the lamp, this circuit being frombattery through the interrupter 25, left-hand alternate contact of relay10, alternate contact of supervisory relay 6 and supervisory lamp 11 toground. The operation of relay 10 opens its left-hand normal contactwhich is in circuit with the lower and operating winding of listeningrelay 7 (of cord circuit F), so that this relay is prevented fromoperating, although the alternate contact of supervisory relay 6, whichis in the operating circuit for this listening relay, is closed. Thesupervisory lamp 11 continues to flash until subscriber C has restoredhis receiver to the switch hook, or until the operator has inserted thecalling plug of cord circuit E into the jack of BS line. The insertionof the calling plug of this cord circuit E into the jack of HS linecauses the operation of sleeve relay 9, which opens its right-handnormal contact, permitting relay 7 of cord circuit E to release. Therelease of this relay removes battery from the right-hand winding ofrelay 10 of cord circuit F, which releases, closing its lefthand normalcontact, whereupon listening relay 7 of cord circuit 13 operates over acircuit similar to that traced for relay 7 of cord circuit E. Therelease of relay 10 also removes the interrupter 25 from the circuit ofthe supervisory lamp 11, which thereupon ceases to flash. Theconnections between subscribers C and D may now be completed in the samemanner as hereinbefore described in connection with the completion ofconnec-.

tions between subscribers lines A and 13.

Suppose that the operator, upon receiving the disconnect signals fromsubscribers A and B, does'not immediately withdraw the plugs from thejacks, and suppose further that after having restored the receivers tothe switch hooks, subscriber A wishes to initiate another call. Theremoving of the receiver from the switch hook will cause supervisorylamp 11 of cord circuit E to flash intermittently. The manner in whichthis is accomplished will now be described. Upon restoring the receiverto the switch hook, the supervisory lamp 11 was lighted to furnish adisconnect signal, and relay 10 was operated over a circuit from batterythrough the left-hand alternate contact of relay 9, normal contact ofsupervisory relay 7 ceiver is removed from the switch hook by subscriberA, the operation of supervisory relay 6 completes a circuit from batterythrough the interrupter 25 and supervisory lamp 11. The operator, uponobserving this flashing signal, actuates key 30 to release relay 10 andremove the interrupter from circuit relation with supervisory lamp 11,and causes the operation of listening relay 7 to connect the operatorstelephone set 12 to the talking strands of cord circuit E. The operatingcircuit for relay 7 may be traced from battery through the left-handalternate contact of relay 9, alternate contact of key 30 and the upperwinding of relay 7 to ground. After ascertaining subscriber As wants,the operator may restore key 30 to normal position, withdraw the callingplug from Bs line and complete'connection from As line to any otherdesired.

That is claimed is:

1. In a telephone exchange system, subscribers lines terminating at acentral oflice, link circuits for interconnecting the lines, anoperators telephone set, a listening relay for each link circuitoperating upon the connection thereof with a calling line to include theoperators telephone set in circuit therewith, and a second relayconditioned for operation upon the operation of the listening relay of abusy link circuit and operated upon the connection of another linkcircuit with another line to prevent the actuation of the listeningrelay thereof.

2. In a telephone exchange system, subscribers lines terminating at acentral office, link circuits for interconnecting the lines, anoperators telephone set, a listening relay for each link circuitoperating upon the connection thereof with a calling line to include theoperators telephone set in circuit therewith, and a second relayconditioned for op eration upon the actuation of the listening relay ofa busy link circuit and operated upon the connection of another linkcircuit with another line to open the circuit of and prevent theactuation of the listening relay thereof.

3. In a telephone exchange system, subscribers lines terminating at acentral office, link circuits for interconnecting the lines, anoperators telephone set, a listening relay for each link circuitoperating upon the connection thereof with a calling line to include theoperators telephone set in circuit therewith, a second relay for eachlink circuit, and a circuit for each second relay open at two points,the operation of the listening relay of a busy link circuit closing onebreak in the circuit of the second relay of another link circuit, thesecond break thereof being closed upon the connection of said anotherlink circuit with another line to actuate said second relay thereof andprevent the operation of the listening relay thereof.

a. In a telephone exchange system, subscribers lines terminating at acentral ofiice, link circuits for interconnecting the lines, anoperators telephone set, a listening relay for each link circuitoperating upon the connection thereof with a calling line to include theoperators telephone set in circuit therewith, and a second relay foreach link circuit, the second relay of another link circuit beingconditioned for operation upon the operation of the listening relay of abusy link circuit and operating upon the connection of said another linkcircuit with another line to prevent the operation of the listeningrelay thereof.

5. In a telephone exchange system, subscribers lines terminating at acentral office, link circuits for interconnecting the lines, anoperators telephone set, a listening relay for each link circuitoperating upon the connection thereof with a calling line to include theoperators telephone set in circuit therewith, a second relay conditionedfor operation upon the operation of the listening relay of a busy linkcircuit and operated upon the connection of another link circuit withanother line, a signaling device associated with said another linkcircuit, and interrupter mechanism brought into circuit with thesignaling device upon the operation of said second relay.

6. In a telephone exchange system, subscribers lines terminating at acentral office, link circuits for interconnecting the lines, anoperators telephone set, a listening relay for each link circuitoperating upon the connection thereof with a calling line to include theoperators telephone set in circuit there with, a second relayconditioned for operation upon the operation of the listening relay of abusy link circuit and operated upon the connection of another linkcircuit with another line, a signaling device associated with saidanother link circuit, interrupter mechanism brought into circuit withthe signaling device upon the operation of said second relay, and meansfor deenergizing the listening relay of said busy link circuit and thesecond relay upon the connection of the busy link circuit with a calledline.

7. In a telephone exchange system, subscribers lines terminating at acentral oiiice, link circuits for interconnecting the lines, anoperators telephone set, a listening relay for each link circuitoperating upon the connection thereof with a calling line to include theoperators telephone set in circuit therewith, a second relay conditionedfor operation upon the operation of the listening relay of a busy linkcircuit and operated upon the connection of another link circuit withanother line to prevent the actuation of the listening relay thereof,and means operating upon connection of the said busy link circuit with acalled line for causing the deenergization of the listening relaythereof and the second relay to actuate the listening relay of saidanother link circuit.

In witness whereof, I hereunto subscribe my name this 24th day of May,A. DJ 1916.

LEWIS I-I. JOHNSON.

Gopies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. O.

